Years ago I read a psychometric study of how people use computing
systems as a function of the time between a user-initiated action and
the system's response. The conclusion of the study was that if more
than ca 1.5 seconds elapsed, the delay would begin to affect what the
user then did. For example, this study suggested, if I put a query to
a system and more than the threshold delay occurs, then I will begin
to censor subsequent queries based on some assessment or other that I
make of the probability of a useful response. The conclusion seems
quite plausible. Consider, for example, unavoidable delays in
conversation between saying something and getting a response. Spontaneity goes.

My question is, can anyone here give me a reference to this or any
similar study?